1. Field of the Invention
The present invention relates to a pressure pulse wave sensor that detects a pressure pulse wave from a body surface of a living being and particularly to such a pressure pulse wave sensor that includes a two-dimensional pressure sensing portion for detecting a pressure pulse wave, and also to an analyzing apparatus that analyzes a pressure pulse wave detected by a pressure pulse wave sensor.
2. Related Art Statement
There is known a pressure pulse wave sensor that is worn on a body surface of a living being and detects a pressure pulse wave from the body surface. For example, there is a pressure pulse wave sensor including a two-dimensional, pressure sensing portion. (cf. Patent Document 1 (Japanese Patent No. 3062202)). In the case where the pressure pulse wave sensor that detects the pressure pulse wave from the body surface is used, it is needed to place the pressure sensing portion of the sensor at a position right above a target-signal producing portion such as an artery. In the case where a pressure sensing portion has a linear shape, a range in which a pressure pulse wave sensor including the sensing portion can be suitably worn is narrow and accordingly it is considerably difficult to locate the sensor at an appropriate position. In contrast, in the case where a pressure sensing portion has a two-dimensional shape, a range in which a pressure pulse wave sensor including the sensing portion can be suitably worn is wide and accordingly it is easy to locate the sensor at an appropriate position.
However, the sensor disclosed by Patent Document 1 has a problem that a press surface of the sensor is defined by a surface of a substrate formed of a monocrystalline silicon and accordingly the press surface has difficulty in fitting a curved shape of a body surface of a living being. Therefore, an accuracy of a pulse wave detected by each of pressure sensing elements arranged in the press surface (i.e., the pressure sensing portion) is not sufficiently high.